最近对数学感兴趣，偶尔看到了数学黑洞的概念，尝试用JS实现了一下：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>数学黑洞</title>
<script type="text/javascript" src="js/jquery-2.2.1.min.js"></script>
<script type="text/javascript">
$(function() {
$("#btn").click(function() {
var number = $("#number").val().trim();
if (!isNaN((number))) {
while (number != 123) {
var number_total = number;
var total = 1;
while (number_total > 10) {
number_total /= 10;
total++;
}
var total_start = total;
var even = 0;
while (total > 0) {
if (Math.floor((number / Math.pow(10, (total - 1)))) % 2 == 0) {
even++;
}
total--;
}
var odd = total_start - even;
number = even + "" + odd + total_start;
}
alert("last_number=" + number);
}else{
alert("请输入整数数字！");
}
})
})
</script>
</head>
<body>
<input id="number" type="number" placeholder="请输入整数数字！" />
<button id="btn">确定</button>
</body>
</html>
